Release controlled formulation refers to a drug delivery system used to release a biologically active ingredient such as a drug over in a controlled manner over a long period of time, e.g. 6 to 24 hours, such as in a sustained manner or in a pulsed manner. The release controlled formulation is advantageous that it can be taken less frequently and it keeps steadier levels of the drug in the bloodstream. Furthermore, it can exhibit a desired blood level pattern through a pulsed-type release at specific times. As such, the release controlled formulation can optimize the blood level of the drug as desired, maximize its efficacy, and reduce adverse reactions caused by instant release of the drug. In addition, it can improve patient convenience by controlling drug administration intervals.
Various drug delivery systems for release control have been developed and put into use, including Alza's Osmotic Release Oral Systems (OROS®). However, a formulation based on a single system often results in breakdown of the overall system due to occurrence or deficiency of specific factors or components, which may cause severe adverse effects through instant drug release.
Methylphenidate is a psychostimulant drug acting on the sympathetic nerves, mainly the central nervous system. It is commonly used to treat attention-deficit hyperactivity disorder (ADHD), most commonly diagnosed in children of 6 years or older and juveniles. Usually, it is taken twice a day (in the morning and before lunch). But, sustained-release formulations that can be taken once a day are preferred since the patient frequently forgets to take the medicine at the lunch hour or does not want to be known to have the disorder.
Some existing sustained-release techniques employ a multiparticulate modified release system including a combination of immediate-release particles and modified-release particles of methylphenidate. The immediate-release particles are formed without a polymer coating on the drug layer, so that the drug is released immediately. However, since the bitter taste of the drug is not masked due to the absence of the polymer coating, they are inapplicable to the formulations that are disintegrated in the mouth, such as orally disintegrating tablet, chewable tablet, etc.
Accordingly, there is a need of a composition for release control that can stably control the release pattern of methylphenidate and mask the bitter taste of methylphenidate for a predetermined time upon exposure to the oral environment.